Processes for manufacture or production of hard disk drives (HDDs) commonly involve writing, onto the surface of the disk or disks, marks or sectors which are used in properly positioning the HDD head during normal read/write use, typically using a tracking servo approach. These sectors or blocks are commonly called servo sectors or servo blocks. In many common HDD production facilities, the servo sectors or blocks are written onto the surfaces of the HDD disks using a device, which is configured especially for this purpose, called a servo track writer (STW). In general, it is desirable to provide a high degree of accuracy in the placement of the servo tracks, sectors or blocks. Accuracy of placement has become more important as disk capacity has improved by increasing data density.
One of the potential sources of inaccuracies is vibration, which may be transmitted to the servo track writer and/or any HDD coupled thereto. The vibrations can have any of a number of origins including vibrations in the building where the STW equipment is placed. Vibrations in the building can arise, e.g., from other equipment in the building, human walking or other movement, environmental sources such as wind, seismic vibrations and the like. Various approaches have been used in an attempt to isolate the STW (and/or in the HDD which is coupled thereto) from such vibrations. However, it is believed that there is room for improvement in STW vibration isolation techniques and/or apparatuses. Accordingly, it would be useful to provide apparatuses, methods and systems which can improve STW vibration isolation, e.g., by reducing or eliminating transmission of vibrations to the STW.
In a typical HDD production facility, there are costs associated with the space occupied by various production equipment. Such costs can be especially of concern in connection with servo track writer equipment or other equipment which is typically located in a clean room having relatively high costs, per square foot, of design, configuration, maintenance, etc. Accordingly, it would be useful to provide a system, method and apparatus for vibration isolation which has a relatively small average footprint and/or occupies a relatively small volume.
In some approaches, multiple servo track writers are mounted on a heavy mass such as a granite block, typically weighing hundreds of pounds. This approach has a relatively high capital cost, typically requires large amount of floor space, as well as specially-designed floors and stands, is difficult to change, expand or move and is difficult to handle in transport. Accordingly, it would be useful to provide an isolation device which is space-effective, relatively inexpensive, and relatively easy to accommodate, design, change and/or move.
In some approaches, STWs are mounted on active vibration isolation devices which sense oscillations or other motions and provide actuators, such as motors, pneumatic devices and the like, to cancel the motion (e.g. by applying, to the external vibration source, an opposite or out-of-phase motion). Such devices, unfortunately, have a relatively high capital cost and typically occupy a relatively large floor space. Any disturbance that occurs is typically easily transferred to all of the STWs in the system and the system tends to be prone to rocking motion in response to external disturbance. Further, pneumatic active damping typically requires special pneumatic supply arrangements. Accordingly, it would be useful to provide STW vibration isolation which has a relatively low capital cost, occupies small space, has a resistance to rocking or other disturbance in response to external forces and can be implemented without providing special supply arrangements.
In some approaches, STWs are mounted on platforms that are positioned on passive elastomer dampers. While this approach is relatively low cost, it is not especially effective at isolating vibrations, is especially susceptible to ground vibrations, and typically occupies a large floor space.
At least some previous vibration damping devices, such as spring-based dampers, are configured to provide the desired vibration dampening for a particular mass and may be relatively sensitive to changes in the weight or mass of the vibration-isolated device or region. In particular, isolation spring devices, in order to be effective, typically require the servo track writer nest or support to be very light in order to be effective. In general, using only linear or spring isolators, a heavier isolated mass requires stiffer springs, effectively reducing the damping and isolation of the spring-mass system. As a result, with such devices, it can be necessary to undergo (typically expensive and time-consuming) redesign of the isolation (damping) device in order to accommodate a new or modified design of an STW (or other vibration-damped device). Further, isolation springs can be relatively ineffective in blocking high-frequency vibration components. Accordingly, it would be useful to provide a vibration isolation apparatus, system and method which blocks high frequency vibrations, and which is relatively insensitive to changes in weight of the vibration-isolated device, preferably in a manner to provide substantially consistent characteristics for predictable damping and isolation.
Many previous spring-mass devices have a relatively large number of moving parts and/or require substantial maintenance for desired operation. Accordingly, it would be useful to provide a vibration isolation device which has relatively few moving parts and/or has a reduced need (compared to, e.g., spring-mass devices) for maintenance, preferably, in a manner such that the static or neutral position for the isolated device is achieved with little or no need for adjustment, such that the device is preferably substantially self-aligning.